>You can find a list of Bitcoin script shortcomings in the Ethereum whitepaper and Ethereum Design Rationale document.

Ah, Ethereum, the ultimate crypto-currency vaporware. When did vbuterin announce it, over a year ago now?

There's a reason the Bitcoin script is simple; because it does everything we want Bitcoin to do (facilitate economic transactions) and it's simple enough that we can be sure it works properly.

If Ethereum actually releases, I'll take that into consideration for my judgement of more complex script schemes.

Yes, Bitcoin is "single-token". What's the downside of this? Why do I care if I need an external registry for non-standard tokens? For tokens to have any effect in the real world (e.g. economic value), you need some form of "external asset registry" no matter what. In most cases, this comes in the form of the seller passing judgement on the value of the token.